Need help with i7 8700k OC

Hey guys. Just need some assistance with my 8700k OC. Right now I got it stable(ish) at 4.7GHz on all cores in realbench. Issue is I see the CPU throttling in HWmonitor. It will run at 4.7GHz for maybe a minute then slow down to around 4.1GHz but I don’t think it’s due to thermals as it runs in the 88C-92C range at those settings. Also I am wondering what is causing my instability as on a whim I turned the LLC down from level 5 to 4 and put the CPU VCCIO and CPU SA voltage from around 1.0V to auto and it ran the stress test for far longer and actually managed to pass a 15 minute realbench test after I turned the bclk down from 100.05 to just 100. When looking in the bios the VCCIO and SA voltage are a bit higher an auto than what I had them set to.

Anyways for AVX workloads I don’t want to push the CPU further as it runs too hot for my liking but once it’s nice and stable I want to OC further for non AVX loads.

System specs:
i7 8700k
Asus Maximus X Hero mobo
G.Skill TridentZ RGB 16Gb @ 3000MHz 16-18-18-38 RAM
Asus GTX 1070 Ti @ 2050MHz
Corsair H100i V2 cooler
Corsair AX1200i psu (waaay overkill lol)
and a couple SSDs and a HDD

As for bios current bios settings when I finally got it to pass 15 minute realbench test:
XMP DDR4-3000 16-18-18-38-1.35V profile
bclk 100.00
disabled Asus multicore enhancement
SVID behavior set to best case scenario
AVX offset = 2 (been fiddling with this but not sure if it matters since the cpu drops to around 4.1GHz in less than a minute or so)
CPU LLC level 4
CPU current capability 110%
CPU core/cache current limit max = 255.50 (not sure what this is, bios description said set to that to prevent throttling so I tried it to see what happens in realbench and there’s no difference)
CPU core/cache voltage in manual mode at 1.280V (cpuz reports this in windows and it drops to 1.232V under stress test)
DRAM voltage is set to 1.35V but seems to stick to 1.344V unless I turn it up to 1.36V
IA AC Load Line set to 0.01
IA DC Load Line set to 0.01 (not sure what either of these IA things are)
Everything else left at auto / default settings for settings related to OC.

Anyways sorry for the long post I just wanted to give as much info as I thought was necessary from the start. I want to do this overclock right this time. Last time I really did a proper OC was with my i7 950 but I didn’t really push it, got it up to 4.1GHz without much fuss and it could sit in P95 all day and stay in the low 60C range so I just called it a day. Never really properly OCed my 4770k either so I want to do it right with this one and get it fine tuned and dialed in. I can also upload what dump files say from the crashes if anyone finds it necessary.

Thanks for any help guys! :slight_smile:

You have cooling on the CPU VRM?
I have an 8700k on an Prime z370 and i can get to 5 Ghz all cores with nothing but a V-Core bump of 1.3V and it only 80c on the core with a cheap AIO

Yeah my mobo has a pretty beefy heatsink on the vrm. I can stress it later and report back at what my vrm temps are.

You should try to put a small fan over the VRM, if its not the cpu itself throttling due to high temps, its most likely the VRM temps holding you back :wink:

I had to put a monoblock on my 7820X to crack 4.7 ghz!